using System;
using System.Collections.Generic;
using System.Globalization;

using Server.Commands;
using Server.Mobiles;

namespace Server.Custom
{
    /// <summary>
    ///     Produces real kill credit inside a participation area, without a game client.
    ///
    ///     ── What this can drive, and what it cannot ───────────────────────────────────────────
    ///
    ///     The participation ledger counts two things: presence, and kill credit. Only one of them
    ///     is reachable from a headless rig, and the split is worth stating rather than discovering.
    ///
    ///     **Presence needs a connected client.** The sweep credits online players — `NetState !=
    ///     null` — which is the correct test and not one a probe should loosen: a character parked
    ///     in Britain and logged out for eight hours did not attend anything, and a ledger that said
    ///     otherwise would put people at the top of a leaderboard for being AFK. There is no way to
    ///     produce a NetState here short of writing a client, so presence accrual is exercised by a
    ///     real login and not by this file.
    ///
    ///     **Kill credit needs none.** `EventSink.CreatureDeath` fires for a creature killed by any
    ///     means, `Mobile.DamageEntries` is populated by real damage, and the area test is a
    ///     coordinate comparison. So the whole of the credit path — the damager filter, the
    ///     per-damager fold, the area test applied to the DAMAGER rather than only the corpse, the
    ///     member cap — runs exactly as it would in a fight.
    ///
    ///     What it does, in order: moves two real player mobiles to the venue, spawns a creature
    ///     there, damages it unequally from both, and kills it.
    ///
    ///     Test scaffolding. Never deployed; `deploy.ps1` copies only `overlay/`.
    ///     In game: `[partprobe <map> <x> <y>`. From a headless rig, through
    ///     `BridgeRigDriver`'s `partprobe` verb — the two ship together for that reason.
    ///     **Moves players and spawns and kills a creature. Rig only.**
    /// </summary>
    public static class BridgeParticipationProbe
    {
        public static void Initialize()
        {
            CommandSystem.Register("partprobe", AccessLevel.Administrator, Probe_OnCommand);
        }

        [Usage("partprobe <map> <x> <y>")]
        [Description("Moves two players to a point, spawns a creature there and kills it.")]
        private static void Probe_OnCommand(CommandEventArgs e)
        {
            if (e.Length < 3)
            {
                Say(e.Mobile, "partprobe <map> <x> <y>");
                return;
            }

            Run(e.Mobile, e.GetString(0), e.GetInt32(1), e.GetInt32(2));
        }

        public static void Run(Mobile from, string mapName, int x, int y)
        {
            var map = MapByName(mapName);

            if (map == null)
            {
                Say(from, "partprobe: unknown map " + mapName);
                return;
            }

            var players = FindPlayers(2);

            if (players.Count < 2)
            {
                Say(from, "partprobe: need two player mobiles in the world; found " + players.Count);
                return;
            }

            var z = map.GetAverageZ(x, y);

            for (int i = 0; i < players.Count; i++)
            {
                // Spread them a tile apart so neither lands inside the other, and so the area test
                // is answering about two distinct points rather than one.
                players[i].MoveToWorld(new Point3D(x + i, y, z), map);
                Say(from, String.Format(CultureInfo.InvariantCulture,
                    "partprobe: {0} moved to {1} ({2}, {3})", players[i].Name, map.Name, x + i, y));
            }

            var victim = new Mongbat();
            victim.MoveToWorld(new Point3D(x, y + 1, z), map);

            // Real damage through the real path, unequal so the fold is doing something: the
            // ledger credits one kill per damager regardless of how much they did, and a table
            // where both did the same amount could not show that.
            //
            // **Both amounts are small on purpose, and the first run of this probe is why.** A
            // Mongbat has around thirty hit points, and an opening blow of 40 killed it where it
            // stood -- so the SECOND damager never landed a hit, `DamageEntries` held one name,
            // and the ledger correctly credited one player. The frame looked like a plugin bug
            // crediting only the killer and was a rig artefact. A probe that means to produce two
            // damagers has to leave the creature alive to receive the second one.
            var hit = Math.Max(1, victim.HitsMax / 10);
            victim.Damage(hit * 2, players[0]);
            victim.Damage(hit, players[1]);

            Say(from, String.Format(CultureInfo.InvariantCulture,
                "partprobe: {0} spawned at ({1}, {2}) and damaged by {3} and {4}",
                victim.Name, x, y + 1, players[0].Name, players[1].Name));

            // Killed on the next tick rather than inline, so the damage above has actually been
            // registered against the creature before CreatureDeath reads the entries.
            Timer.DelayCall(TimeSpan.FromSeconds(1.0), () =>
            {
                victim.Kill();
                Say(from, "partprobe: killed; the credit should now be on the ledger");
            });
        }

        private static List<PlayerMobile> FindPlayers(int count)
        {
            var found = new List<PlayerMobile>();

            foreach (var m in World.Mobiles.Values)
            {
                var pm = m as PlayerMobile;

                if (pm == null || pm.Deleted || pm.AccessLevel > AccessLevel.Player)
                    continue;

                found.Add(pm);

                if (found.Count >= count)
                    break;
            }

            return found;
        }

        private static Map MapByName(string name)
        {
            for (int i = 0; i < Map.Maps.Length; i++)
            {
                var map = Map.Maps[i];

                if (map != null && String.Equals(map.Name, name, StringComparison.OrdinalIgnoreCase))
                    return map;
            }

            return null;
        }

        private static void Say(Mobile to, string text)
        {
            if (to != null)
                to.SendMessage(text);
            else
                Console.WriteLine("[PartProbe] " + text);
        }
    }
}